ALLIANCES OF PLANTS. 47 



Exogens, as containing the most highly developed plants, occupy 

 the middle position, and at equal distances stand the Endogens, Cor- 

 mogens, and Thallogens, with their respective intermediates between. 

 Everything stands pretty near to its related forms ; and if we think of 

 the noblest Exogen as the heart of a solid sphere, over the surface of 

 which are diffused the lowest kinds of Endogens and of imperfect 

 plants, the successively nobler lying intermediately and filling up the 

 space, we shall understand how things stand related in actual fact, 

 and how every plant has alliances on all sides. That this is the 

 correct and philosophical view of the matter, is shewn at length in 

 the author's work named below, whei'ein also are copious illustrations 

 from the analogies of the Animal Kingdom.* 



But on paper we must needs proceed in a straight line, taking 

 things in the most natural succession that the exigencies of the pen 

 will permit. In the present volume accordingly the families will be 

 described in the order they have been mentioned, and of which the 

 following table is a summary : — 



PERFECT, or FLOWERING PLANTS. 



Class 1. Exogens. 



Section 1. Bisexual Exogens. 



Group 1. Ovary free and enclosed; stamens 



on the receptacle. (Fig. 58.) 

 Group 2. Ovary free and enclosed ; stamens 



on the perianth. (Fig. 59.) 

 Group 3. Perianth on the summit of the 

 ovary. (Fig. 50.) 

 Section 2. Unisexual Exogens. 

 Class 2. Endogens. 



Section 1. Petaloid. 

 Section 2. Glumaceous. 

 The Fir-tree family, intermediate between Exogens and 



Cormogens. 

 The Tamus family, intermediate between Exogens and En- 

 dogens. 

 IMPERFECT, or FLOWERLESS PLANTS. 

 Class 3. Cormogens. 

 Class 4. Thallogens. 



* " Life ; its Nature, Varieties, and Phenomena." Chap, xxix., p. 342. (Ed. 2.) 



